Modified methylated melamineformaldehyde compositions



Patented July 20, I954 MODIFIED METHYLATED MELAMINE-- FORMALDEHYDE COMPOSITIONS Ralph F. Nickerson, Marblehead, Mass, assignor to Monsanto Chemical Company, St. Louis, Mo a corporation of Delaware No Drawing. Application February 3; 1951, Serial-No. 209,319

12'Claims. 1

The presentinvention relates to-modified compositions comprising methylated melamine-formaldehyde condensationproducts .and to methods of preparing such compositions, and more particularly to modified compositions comprising methylated melamine-formaldehyde condensation products for use in the finishing of textile materials such as cotton fabrics.

It has been proposed heretofore to prepare aqueous solutions. of methylated melamine-formaldehyde condensation products by reacting methyl alcohol with monoor polymethylol melamine to provide methyl-ethers of the melamine-formaldehyde condensation product in an aqueous solution. The solutions thus obtained are known to contain small amounts of free formaldehyde and the condensation products therein often contain unetherified methylol groups. impregnate various textile materials including cotton fabrics with such'solutions, after which the impregnated textilematerial is calendered as, for example, intcertainttypes of wearing apparel, it is considereddesirable, in the case of some types of fabrics suchascurtainfahrics and in other uses, to obtain a fabricor textile mate'- rial which has a crisp or stiffened finish. Inthe case of'c'otton fabrics which are used in makingcurtain fabrics, for example, it is desired to pro vide'a crisp or stiffened finish. It is extremely di ncult, however, to-obtain a crisp finish with the aqueous solutions of methylated melamineformaldehyde condensation products described above. Moreover, ithas been found that cotton fabrics impregnated withsuchsolutionsand then cured-have low tear strength and thus aregenerally unsatisfactory mor many of the uses forwhich they would-ordinarily be employed.

,Inaccordance with thepresent invention, it

ispossible to provide modified aqueous solutions of methylated melamine-formaldehyde condensation products which when used to impregnate cotton fabricsfor example; and then cured, provide'a-cotton'fabric having a crisp permanent finish and'a considerably. higherrtear strengththan is possible with-the priorart' solution described above. I.

It has also been proposed heretofore to Itv is .one object of this invention to'provide a process for preparing modified aqueous compositions comprising methylated melamine-formaldehyde condensation products which when applied. to textile materials, particularly cotton fabrics, and curedprovide, a material having a crisp substantially. permanent finish, and good tear. strength.

It is a further, objectof this inventionto pro- .vide modified aqueous solutions of methylated melamine-formaldehyde condensation products, which solutions are substantially free of uncombined formaldehyde and are infinitely dilutable with waterwithout precipitationof the con- H densation product.

Still further objects and advantages of this invention will appear in thefollowing description and the appended claims.

The present invention, in brief, is based on the discovery that when certain nitrogen-containing compounds, as, for example, urea or ammonia are added to an infinitely dilutable alkaline aqueous solution of methylated melamine-formaldehyde condensation products'containing free formaldehyde and the resulting'mixture is heated until the solution is free of uncombined formaldehyde and the particle size of the condensation prod not is increased and the heating is discontinued while the solution is still infinitely dilutable, a.

composition is obtained which when applied to cotton fabrics, for example, and then cured provides. a finished material which has a considerably higher tear strength and a crisper finish than the same fabric which is treated withthe initialformaldehyde containing solution of the,

and carbon andwhichinsome instances also in-.. clude oxygen and sulfur atoms but; no other atoms. Urea, thiourea. andmelamine are examples of such compounds. Other suitable compounds which-may be mentioned include mono-- ethanolamine, diethanolamine, water solublealkylene polyamines s -ioh as, ethylene diamine, 1

water-soluble alkyl primary and secondary amines containing 3 to 6 carbon atoms such as propyl amine or diethyl amine and the like. Dicyandiamide is specifically excluded, however, since it forms condensation products which polymerize under alkaline conditions, and is not suitable for the purposes of this invention.

Urea is one of the cheapest of the above described nitrogen-containing compounds and gives the best results and accordingly is preferred for the purposes of the invention. Ammonia and melamine are the nitrogen-containing compounds of second choice.

Heretofore, the aqueous solutions of methylated melamine-formaldehyde condensation products which have been prepared commercially for textile purposes contain small amounts, that is, from about 0.1 to on the weight of the solution, of free formaldehyde. This free formaldehyde is present either because an excess amount of formaldehyde is used in preparing such condensation products and is not combined with the melamine and/or because the polymethylol melamines which are reacted with methanol to form the methylated melamineformaldehyde condensates are not completely etherified and contain some unetherified methylol groups which dissociate partially in aqueous solutions to form free formaldehyde according to the following equation:

C:N-CH2OCH: n N \N H20 I! CH3OOH2II\TO (LN-onion Di-(methoxymethyl) monomethylol melamine Dimethoxymethyl melamine The above equilibrium is not strictly equal and the tendency is stronger for the unetherified methylol group to dissociate into free formaldehyde and the amino group as illustrated in the right hand side of the equation.

It is believed that the free formaldehyde in the solution is what causes the excessive loss in tear strength when the condensation product is applied, for example to cotton fabrics. By reacting the free formaldehyde in such solutions with an amount of the nitrogen-containing compounds (such as urea) sufiicient to react with all of the free formaldehyde in the aqueous solution of the methylated melamine-formaldehyde condensation product, it is possible in accordance with this invention to eliminate the free formaldehyde from the solution and thus provide compositions which when applied to cotton fabrics and cured have a high tear strength compared to cotton fabrics treated with the initial solutions. Moreover, by simultaneously increasing the particle size of the condensation product by heating, it is possible to prepare a composition which provides a crisp permanent finish when applied to textile fabrics.

As has been pointed out previously herein the aqueous solutions of methylated melamineformaldehyde condensation product, which solutions are one of the essential starting materials in the process of this invention, hould be alkaline and infinitely dilutable, that is, infinitely dilutable with water. Such solutions should have a pH of at least 8.0 and not greater than 11, and preferably within the range of 9.0 to 10.5. Such solutions generally also contain from about 0.05 to 5% by weight of free formaldehyde, and will, in most instances, contain from 0.1 to 3% by Weight of free formaldehyde depending on the manner in which they are prepared. The concentration of the condensation product in such solutions may vary widely, for example, between about 10 and by weight based on the solution. However, since the present invention is directed primarily to the treatment of commercial solutions, it is preferred to employ aqueous solutions which contain about 50 to 80% by weight of the methylated melamine-formaldehyde condensate. Colloidal solutions of methylated methylol melamines are not contemplated herein.

The methylated melamine-formaldehyde condensate in the aqueous solutions described immediately above should be water-soluble and the aqueous solutions thereof should be infinitely dilutable, but the condensates may vary considerably in chemical composition. For practical purposes, the condensation products employed. herein should preferably contain at least 2 mols of combined formaldehyde and 1 mol of combined methanol for each mol of melamine or, stated in another way, they preferably should contain at least an amount of combined formaldehyde and. combined methanol equivalent to monomethoxymethyl monomethylol melamine. Condensation products containing 6 mols of combined formaldehyde and 6 mols of combined methanol per mol of melamine and the intermediate condensation products are also useful. Best results are obtained by starting with aqueous solutions of condensation products which contain from 2 to 5 mols of combined formaldehyde and 1 to 3.5 mols of combined methanol for each mol of melamine and these products are accordingly preferred.

The starting solutions of methylated methylol melamine condensation products used in the processes of this invention may be prepared in various ways. Thus, in general, they may be prepared by first reacting from about 3 to 8 mols of formaldehyde in an alkaline aqueous solution with melamine, adding methanol and then reacting the resulting ingredients under acid conditions, after which the solution is made alkaline. One suitable method of preparing such solutions comprises first reacting melamine and an aqueous alkaline solution of formaldehyde, using about 3 to 8 mols of formaldehyde for each mol of melamine, at a temperature of about 60 to C. until the melamine is substantially dissolved.

In the preparation of highly methylolated products, the melamine first dissolves, and then the addition product of the formaldehyde and melamine precipitate from the solution as the number of mols of combined formaldehyde per mol of melamine approaches 5 to 6. The methylating agent, which is preferably methanol, is then added to this solution. In general, about 10 to 30 mols of methanol are employed for each mol of melamine used, depending upon the degree of methylation or etherification desired. The solution is then acidified to a pH between about 2 and 5 with a strong mineral acid such as hydrochloric acid, phosphoric acid and the like.

a The resulting solution is then heated to a temneous solution is obtained; and; thewcondensation:

product contains the: desired: amount; of combined methanol, after whichrthe solutionsisyneue tralized to apH between 8 and111 withanalkaline compound,i-p-referablyaan alkali: metalahydroxide;

such as caustic-sodaaoricaustic'potasknx The solution is then-.cooledlto aboutrlO ltowflfirC. Precipi'tated .salts. formed by: thee-neutralization. oi the minerallacid with the ralka linexcompoundlare. preferably removed at... this-stage by filtrationg. The-solution is then concentrated. to: the". desired soli'ds; content by centrifuging: or the like;

heating. below: 60 C. undercvacmnm In carrying out the processesuoi" this invention. the 1 ormaldehyde'. .reactablez. nitrogenacontainingr compound such as: urea.or'ammoniaziisxadded;to the alkaline aqueous solution of methylated.

size of the condensation product. has: increased to such an extent that: the. product is: not longer infinitely dilutable" with water; Stated in another way,.the heatingzisl discontinued Whilethe solution is still infinitely dilutablei with: water without: precipitating. part of: thee. condensation product; The solution is. then/cooled. Atthis stage the solution is;still.cleaniandihe:particles:

of condensation: productizare belowuthe. colloidal range.

One practical procedure for'determining when the particle size of" the. condensation; product-has beenincreaeed to theproper extentisabythe salt. titer test. The salt titer test-consists in. taking: a sample of the solution and adjusting;its.con+

densation product concentrationto 6% by weight by dilution with water, placing 25 cc. of the 6% solution in a 125 cubic centimeter" Erlenmeyer flask and then adding an aqueous solution containing 26% by weight of sodium chloride until a? point newsprint placed underneath the flask is no longer legible. This .is-"the end point of the test. The number of cubic centimeters of the sodium chloride solution required to bring the solution of: the condensation-producttOPtliiS end. point is the. salt titerz.

In general; the salt: titer 'Of'fl'lfi starting solua tion of the methylated. methylol melaiminer.oon-' densation product at 6% by weight: solidsv is dependent primarily on the degree o'fztimethylolation and etherificati'onof: thecondensationproduct. which contain from about: v2 to 5 mols' o-f combinediormaldehyde and l 3.5 molszsofz com bined methanol per mo1 -of:-melamine:ati6i% by: weight solids normally have. a .saltztiter: between;

about 56 to sowiththe-higher VQJHEJCDI'FI'GSDOIIde-Z ing to the products having the smaller numbe i2 mols of combined formaldehyde and; combined;

methanol. As the number of mole of combined formaldehyde and combined methanol per mol of melamine in theproductof theflstarting solw tion is increased the. salt titer of. thesolutionat.

Thus, a 6% by weight so.-

6% solids decreases. lution of a condensation product: containinge;

mole of combined formaldehyde"andzdtoxfi molsof combined methanol (the. latterrzbeing, the; theojretinal limit) has a salt titeitbetween about iwandi Thus solution of" condensation products Th'ezsalttiterris a-zmeasure'ot thezparlticle size-of.

the smethylated methylol: melamine condensation product. in: solution-providing. the: chemical .oompositiomon'theicondensation productis the same.

- Asthe starting solution. of. the methylated methticular chemical?comnositioniofs thecondensation Thus, in general, this point will beproducti reached in thecase ofpa 6% by weight solution of a" condensation product containing from about 2 to' amolsofzcombined formaldehyde and 1 to 3 mols; of combined methanol per'mol of melamine whenathe sa'lttiterris between about 10 and 35, and preferably between 10 and 20. In the case of a 6% I byweightsolutionof.apcondensation product containingafromgabout. a to mole. of combined form aldehyde: this point" is; generally reached when the saltctiter'istbetweeni about 5. and, 15. In the casezof a:'6.%. by. WeightsoIution of condensation productsicontaining between 5 and 5 mole of combinediiormaldehyle mode to 6 mole of, combined methanol; ,pers moi of;.-melamine,. this point is reached.whemthersalt titer is between about 1 and 5. Ittis thus'iseen thatthe salt titer of. the solution .at 6% by weight solids, after heating, will be betweenabout 351' and 1,,depending on-the ohei lical composition off-then rethylated methylol melamine in. the. solution:

As has-been: pointed: outv previously-herein, the amount offormaldehyde-reactable nitrogcnwcmtaming compound such asv urea .or ammonia which .is addeclashouldbesufficicnt to react with the free;formaldehydegpresent inst-he starting so-- lutiomof thesmethylated methylol melamine 'con densateand-also theireeiormaldehyde which is formed the dissociation. of; the unetherified methylol:.;groupsoaths-melamine molecule. In general; the. amounts of: suoh'compou-nd required will-be betweenabout- 0.5 and 5% by weight based onz-the. weight of the condensate in the solution. However, in someins-tances when the amount of free formaldehyde in the starting solution is. low, it is possible to use amounts of the nitrogen-contaming: compound as'low asill by weight based on the weight off the" condensate in the solution. On. the other. hand, it is possible to use larger amounts of the nitrogen.-eontaining, compound, thatis, up to. 10% by weight based on the we? oftthe.condensateinthe solutionwhen the .ingsolution contains largeamounts of free form.-

aldehyde. or. the. condensate contains about 2 unetherified. methylol. groups per mol of nielamina.

The temperature at. which the alkaline aqueous solution of the. methylated methylol melamine condensationproduct and the nitrogen-containinacompound. such. as. urea is heated. may be varied appreciably. Generally, suitable results are obtained by heating the solution at a tem peraturebetween-about. IG-and 130 C. At temperatureswbetween 10.0. and,130 C. the heating,

shouldbecarried.out ina closed-vessel and under-pressure. If: temperatures below 70 C.. are

usedg-otheriheatin'g period required is usuallyof. tsuch duration that the process is not economical-z.

from a commercial viewpoint. On the other hand, if temperatures above 130 C. are employed, it is diiiicult to control the salt titer and the particle size of the condensation product. The quality and uniformity of the product are best controlled at temperatures between about 90 and 105 C. and these temperatures are accordingly preferred for carrying out the process.

The time required to bring the solution of the nitrogen-containing compound such as urea and the methylated methylol melamine condensation product to the desired particle size or salt titer and to bring the solution to the stage where it is free or substantially free of uncombincd formaldehyde is primarily dependent on the temperature used during the heating period. At solution temperatures of 90 to 105 C., the heating period required is generally between 1 and 5 hours. At temperatures of 70 to 90 C. heating periods of about 12 to 5 hours are normally required. At temperatures of 105 to 130 C. heating periods of 1 hour to minutes are generally required.

Durin the heating period the pH of the solution may drop particularly when urea is used as the formaldehyde-reactable nitrogen-contaim ing compound. This is not objectionable provided the pH of the solution does not drop below 8. However, if the pH of the solution does tend to drop below 8 the pH may be maintained above 8 by adding an alkaline compound such as an alkali metal hydroxide as, for example, caustic soda or an alkali metal carbonate as, for example, sodium carbonate.

After the heating has been carried out to the desired extent as hereinbefore indicated, the solution is cooled to a temperature of about 15 to C. In order to prevent any substantial increase in polymerization or particle size of the condensation product at the end of the heating period, it is preferred to carry out the cooling as rapidly as possible. The cooled solution is preferably adjusted to a pH between 9 and 11 with an alkaline compound such as caustic soda or sodium carbonate if the pH is below 9.

A further understanding of the processes of this invention will be obtained from the following specific examples which are intended to illustrate the invention, but not to limit the scope thereof, parts and percentages being by weight.

EXAMPLE I A. Preparation of aqueous solution of methylated methylol melamine One mol of melamine was reacted with about 4.5 mols of formaldehyde in the form of 37% neutral formalin under reflux at a pH of about 8.6 (glass electrode) at a temperature of 70 C. until the melamine was substantially dis olved. After a further reaction of about 5 minutes, 20 mole of methanol were added and the pH was adjusted to 4.0 (glass electrode) with phosphoric acid. The reaction was then continued for an additional 15 minutes at a temperature of approximately C. The pH of the solution was then adjusted to 10.1 (glass electrode) with caustic soda. The resulting solution was then cooled and filtered and was found to contain 40% methanol, 24% condensation product, 2% free formaldehyde and 34% water. The condensation product in the solution contained about 3.5 mols of combined formaldehyde and 2.2 mols of combined methanol for each mol of melamine. 1 7

The above solution was concentrated to 60% solids by heating the solution at 50 C. under a vacuum. The resulting solution was infinitely dilutabie with water and contained about 0.5% free formaldehyde. This solution had a salt titer of 81 at 6% solids, as determined by the salt titer test hereinbefore described.

Seven hundred parts of this solution and 14 parts of urea were stirred under reflux for 3 /2 hours at a temperature of 96 C. At the end of this time the solution had a salt titer at solids of 12.5 and a pH of 8.1. The solution was cooled rapidly to a temperature of 25 C. and the pH was adjusted to 10.1 with caustic soda. The specific gravity of the solution was 1.181, and the solution was infinitely dilutable with water without precipitation of the condensate therein.

The above solution was diluted with water until it contained 10% solids, and then 1.2% of ammonium thiocyanate, based on the 10% solution, was added as a curing catalyst for the condensate in the solution. A strip of x 80 cotton fabric was immersed in the solution and thoroughly wetted out therein and then passed between squeeze rolls at a pressure of pounds per linear inch. This gave a pick-up of 90%. The squeezed fabric was then framed and dried for 5 minutes at F. and heated for 5 more minutes at 300 F. to cure the condensate to a water-insoluble state.

A strip of the same fabric from the same roll was treated in the same manner with a 10% solution of the methylated methylol melamine condensation product which was not heated with urea and which had a salt titer of 81 at 6% solids.

Both fabrics were tested for tear strength and stiffness, the tear strength being measured by an Elmendorf tearing tester and the stiffness being tested by a Gurley stifiness tester with the following results:

salt Average Solution Used Titer Tear Stiffness Strength Unmodified methylated methylol melamine (not heated With urea) S1 395 4. 0 Modified methylated mcthylol melamine (heated with urea), 14 51 5.0

EXAMPLE II A modified solution of methylated methylol melamine was prepared according to the procedure described in Example I except that am monia was used instead of urea. A solution was obtained which had substantially the same properties as the solution prepared with the urea of Example I. This solution also provided a cotton fabric which was similar in tear strength and rials. *erated cellulosic textile materials such as viscose and cuprammonium rayon fabrics. although the solutions are especially suitable for the treatment of cellulosictextile materials they are also suitable for use on other textile matestiffness tothe' fabric treated with theu1ea-modified. solution of :Example 1.

Although the effects of the-modified :solutions of this invention have been-describedin the examples with reference to cotton fabrics, it is alsopossible to obtain improvedtear strength .and :a crisper finish with 'such solutions .in the case of other cellulosic fabricsand textile mate- Thus good results are obtained on-regen rials made of wool, mixed wool .and'celluloseand on synthetic textile materialsgenerally where improved-tear strength and fa -crisp finishuis desired.

Various modifications and changes in the processes and compositions of thisinvention will characterized -in--that the nitrogen containing compound is urea.

2. A process of modifying aqueous compositions comprising methylated melamine-formaldehyde condensation products which comprises heating at a temperature of '70 to 105 C. a mixture of (1) an alkaline aqueous solution of a methylated methylol melamine condensation product containing 2 to 5 mols of combined formaldehyde and 1 to 3.5 mols of combined methanol per mol of melamine, said solution having a salt titer at 6% by Weight solids between 50 and 90, a pH between 8 and 11, a solids content of 10 to 85% by weight, being infinitely dilutable with water without precipitation of the condensation product and containing from 0.05 to 5% by weight of free formaldehyde, and (2) from 0.1 to 10% by weight, based on the condensation product, of a nitrogencontaining compound selected from the group consisting of ammonium hydroxide, urea, thiourea, monoethanolamine, diethanolamine, watersoluble allcylene poly-primary amines and water-soluble alkyl primary and secondary monoamines containing 3 to 6 carbon atoms, said mixture being heated until the solution has a salt titer at 6% by weight solids between 5 and 20, while maintaining the pH of the solution between 8 and 11, said heating being carried out when at '70 to 90 C. for about 12 to 5 hours and when at 90 to 105 C. for between 5 and 1 hours, and then cooling the solution, said salt titer being determined as defined in the eighteenth paragraph of the foregoing specification.

3. A process of modifying aqueous compositions comprising methylated melamine-formaldehyde condensation products which comprises heating at a temperature of 90 to 105 C. a mixture of 1) an alkaline aqueous solution of a methylated methylol melamine containing from about 2 to 5 mols of combined formaldehyde and 1 to 3.5 mols of combined methanol per mol of melamine said solution having a salt titer at 6% by weight solids between 50 and 90, a pH between 8 and 11, a solids content of 10 to 85% by weight, a free formaldehyde content of 0.05 to 5% and being infinitely dilutable with water without precipitation of the condensation product, and (2) from Eli!) 0.1 to 10% by weight, based on said condensation product, of anitrogen-containingcompound selected from the. group consisting of ammonium hydroxidemrea, thiourea, monoethanolamine, diethanolamine, water-soluble alkylene poly-primary amines and water-solublealkyl' primary and secondary monoamines, said mixture being heated until the solution is substantially tree of uncombined formaldehyde an'dlhasasalt titer at 61% by Weight solids between 5 and 20, While maintainingthe pH of the solution between 8 and 11,

said-heating being carried out "for a period between 5 -and 1 hours-and then rapidly cooling thesolution to between 15 and 3O "C.,-said salt titer being determinedaas defined. in the eight- :eenth paragraph of-the foregoing specification.

4. A- processaccording to claim 3, but further characterized in that theYnitrogen-containing compound is urea.

5. A process according to claim but further characterized in that the nitrogen containing compound -isammonium".hydroxide.

6. Aprocess according. -.to claim 3, but-further characterized in that the -nitrogen-.contai'n"i'ng compound is thiourea.

7. A process according to claim '3, but further characterized .inthat the nitrogen-containing compound ,is monoethanolamine.

81A process ofmodifying aqueous compositions comprising .methylated melamine-formaldehyde condensation products which comprises heating at a temperature of 90 to 105 C. a mixture of (1) an alkaline aqueous solution of a methylated methylol melamine condensation product containing from about 2 to 5 mols of combined formaldehyde and 1 to 3.5 mols of combined methanol per mol of melamine, said solution having a salt titer at 6% by weight solids between 50 and 90, a pH between 9 and 10.5, a solids content of 50 to by weight, a free formaldehyde content between 0.1 and 3% by weight and being infinitely dilutable with water without precipitation of said condensation product, and (2) from 0.5 to 5% by weight, based on said condensation product, of urea, until the solution is substantially free of uncombined formaldehyde and has a salt titer at 6% by weight solids between 10 and 20 while maintaining the pH of the solution between 8 and 10.5, said heating being carried out for a period between 5 and 1 hours, cooling the solution rapidly to between 15 and 30 C. and adjusting the pH of the solution between 9 and 11, said salt titer being determined as defined in the eighteenth paragraph of the foregoing specification.

9. A composition prepared according to the process of claim 11.

10. A composition prepared according to the process of claim 8.

11. A process of modifying aqueous compositions comprising a methylated melamine-formaldehyde condensation product which comprises forming a mixture of (1) an alkaline aqueous solution of a methylated methylol melamine condensation product containing 2 to 5 mols of combined formaldehyde and 1 to 3.5 mols of combined methanol per mol of melamine, said solution having a salt titer, as defined in the eighteenth paragraph of the foregoing specification, at 6% by weight solids between 50 and 90, apH between 8 and 11, a solids content of 10 to by weight, being infinitely dilutable with water without precipitation of said condensation product and containing free formaldehyde, and (2) a nitrogen-containing compound selected from the group consisting of ammonium hydroxide,

urea, thiourea, monoethanolamine, diethanolamine, water-soluble alkylene poly-primary amines and Water-soluble alkyl primary and secondary monoamines containing 3 to 6 carbon atoms, said nitrogen compound being employed in an amount sufiicient to react with all of the free formaldehyde in said solution, heating said mixture to a temperature between '70 and 130 C. until the solution has a salt titer, as defined in the eighteenth paragraph of the foregoing specification, at 6% by weight solids between and 20 while maintaining the pH of the solution above 8, said heating being carried out when at 70 to 90 C. for about 12 to 5 hours, when at 90 to 105 C. for between 5 and 1 hours and when at 105 to 130 C. for 1 hour to 20 minutes, and then cooling said solution.

12. A process of modifying aqueous compositions comprising a methylated melamine-formaldehyde condensation product which comprises heating at a temperature of 70 to 130 C. a mixture of (1) an alkaline aqueous solution of a methylated methylol melamine condensation product containing 2 to 5 mols of combined formaldehyde and 1 to 3.5 mols of combined methanol per mol of melamine, said solution having a salt titer, as defined in the eighteenth paragraph of the foregoing specification, at 6% by weight solids between 50 and 90, a pH between 8 and 11, a solids content of 10 to 85% by weight, being infinitely dilutable with water without precipitation of said condensation product and containing 0.05 to 5% by weight of free formaldehyde, and (2) a nitrogen-containing compound selected from the group consisting of ammonium hydroxide, urea, thiourea, monoethanolamine, diethanolamine, water-soluble alkylene poly-primary amines and water-soluble alkyl primary and secondary mono-amines containing 3 to 6 carbon atoms, said nitrogen compound being employed in an amount sufiicient to react with all of the free formaldehyde in said solution, said mixture being heated until the solution has a salt titer, as defined in the eighteenth paragraph of the foregoing specification, at 6% by weight solids between 5 and 20 while maintaining the pH of the solution between 8 and 11, said heating being carried out when at to C. for about 12 to 5 hours, when at 90 to C. for between 5 and 1 hours and when at 105 to C. for 1 hour to 20 minutes, and then cooling the solution.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,318,560 Ripper May 4, 1943 2,456,568 Scott Dec. 14, 1948 2,466,457 Lynn Apr. 5, 1949 2,529,856 West Nov. 14, 1950 

11. A PROCESS OF MODIFYING AQUEOUS COMPOSITIONS COMPRISING A METHYLATED MELAMINE-FORMALDEHYDE CONDENSATION PRODUCT WHICH COMPRISES FORMING A MIXTURE OF (1) AN ALKALINE AQUEOUS SOLUTION OF A METHYLATED METHYLOL MELAMINE CONDENSATION PRODUCT CONTAINING 2 TO 5 MOLS OF COMBINED FORMALDEHYDE AND 1 TO 3.5 MOLS OF COMBINED METHANOL PER MOL OF MELAMINE, SAID SOLUTION HAVING A SALT TITER, AS DEFINED IN THE EIGHTEENTH PARAGRAPH OF THE FOREGOING SPECIFICATION, AT 6% BY WEIGHT SOLIDS BETWEEN 50 AND 90, A PH BETWEEN 8 AND 11, A SOLIDS CONTENT OF 10 TO 85% BY WEIGHT, BEING INFINITELY DILUTABLE WITH WATER WITHOUT PRECIPITATION OF SAID CONDENSATION PRODUCT AND CONTAINING FREE FORMALDEHYDE, AND (2) A NITROGEN-CONTAINING COMPOUND SELECTED FROM THE GROUP CONSISTING OF AMMONIUM HYDROXIDE, UREA, THIOUREA, MONOETHANOLAMINE, DIETHANOLAMINE, WATER-SOLUBLE ALKYLENE POLY-PRIMARY AMINES AND WATER-SOLUBLE ALKYL PRIMARY AND SECONDARY MONOAMINES CONTAINING 3 TO 6 CARBON ATOMS, SAID NITROGEN COMPOUND BEING EMPLOYED IN AN AMOUNT SUFFICIENT TO REACT WITH ALL OF THE FREE FORMALDEHYDE IN SAID SOLUTION, HEATING SAID MIXTURE TO A TEMPERATURE BETWEEN 70 AND 130* C. UNTIL THE SOLUTION HAS A SALT TITER, AS DEFINED IN THE EIGHTEENTH PARAGRAPH OF THE FOREGOING SPECIFICATION, AT 6% BY WEIGHT SOLIDS BETWEEN 5 AND 20 WHILE MAINTAINING THE PH OF THE SOLUTION ABOVE 8, SAID HEATING BEING CARRIED OUT WHEN AT 70 TO 90* C. FOR ABOUT 12 TO 5 HOURS,WHEN AT 90 TO 105* C. FOR BETWEEN 5 AND 1 HOURS AND WHEN AT 105 TO 130* C. FOR 1 HOUR TO 20 MINUTES, AND THEN COOLING SAID SOLUTION. 